Los Angeles Mayor Antonio Villaraigosa — the chairman of the 2012 Democratic National Convention — said on Wednesday that he favors a gay marriage legalization plank in his party’s platform.

Villaraigosa publicly announced he backs the national party taking a stance on marriage equality, an issue he has long supported, at Wednesday’s POLITICO Playbook Breakfast. President Barack Obama doesn’t support legalization but has said his position is evolving.

During a wide-ranging interview, POLITICO’s Mike Allen at one point asked the recently selected chairman, “Do you think that the Democratic national platform should have a marriage equality plank?”

“I do, I think it’s basic to who we are,” Villaraigosa said. “I believe in family values and I believe that we all ought to be able to have a family and marry if you want to. I don’t think the government should be in that business of denying people the fundamental right to marry.”

As for what the plank includes, however, Villaraigosa said he would leave that up to the convention delegates.

Meanwhile, Villaraigosa offered sharp criticism for the Republican party, saying that the GOP’s policies on immigration, women’s issues and gay marriage don’t match up with mainstream American thinking.

The Democratic mayor warned that Republicans would lose their status as a top tier party if they continue to harp on divisive social issues instead of embracing the middle. He predicted that the Republican party is moving so far to the right it will “become the Whig party of the next millennia.”

“Whigs no longer exist, they’re not here anymore as a party,” Villaraigosa said at the Newseum in Washington. “The fact is, when you hear the Republican candidates on immigration, when you see them and hear them talk about contraception, mammograms, abortion and not the economy, it’s clear to me they’re moving farther and farther away from the mainstream.”

And on immigration — where Villaraigosa said it looks as though Republicans are “certainly not acting worried” about the impact of their policies — the mayor said he expects the harsh policies and rhetoric to backfire.

“This is the first time in modern history that I can recall where a major candidate from either party does not support comprehensive immigration reform. This is the first time I’ve seen the kind of vitriol and scapegoating of immigrants, that kind of rhetoric,” he said.

And the consequences for the Republican Party, he said, will be the loss of an entire voting population and the subsequent decline of the party in the political world.

“I think the consequences are it’s going to make them the Whig party of the next millennia,” he said. “They’re going to lose the Latino electorate. They’re going to lose it for some time.”

But there is a way back for Republicans, he said — by moving to the middle. And one critical area that shouldn’t drive up partisan rancor is transportation and infrastructure, the issue the Los Angeles mayor is currently in D.C. promoting as he lobbies Congress to pass a surface transportation bill that’s currently stalled.

“Every president, Democrat or Republican, every Congress has gotten behind the idea that we have to invest in our highways, our bridges, our roads, our airports,” Villaraigosa said. “The idea that now this is somehow a partisan issue, it boggles the mind.”

Still, the Democratic mayor didn’t leave his own party alone in criticism, particularly slamming Democrats in Sacramento, Calif. for their unwillingness to challenge the “broken status quo” of seniority and tenure in the education system.

“What you find is a real reluctance among Democrats to challenge orthodoxies like seniority and tenure,” he said.

Looking back on Super Tuesday and the 2012 Republican contenders, the Democratic mayor said he “likes the word slog.”

“It conjures images of someone cross-country skiing up hill,” he said. “Look, it’s going to be a long race.”

The main reason for the lengthy primary season, he said, is that Republicans just aren’t satisfied with Mitt Romney.

“Governor Romney may have the delegates ultimately, but what’s crystal clear is that the Republican electorate is not excited about him,” Villaraigosa said. “I don’t think they trust him. You get a sense that Mr. Romney will say anything to get elected, that’s why the flip-flopping over the years, sometimes even in days of one another. It’s clear to me this is going to be a long race. And slogging hits it right on the head.”

And as for life after serving as mayor, Villaraigosa said he looks forward to taking some “time for a little reflection.”

“I want to finish my job, I want to finish it strong. I want to do as much as I can and put the city on a more sustainable path given that we’ve been in the worst financial crisis since the 1930s,” he said. “And then I think it’s time for a little reflection. So If I was a betting person, I’m going to take that time. You never know, obviously things can come up.”